When was Claude Opus 5.5 released?

Anthropic announced it and made it available on 22 September 2026.

How much does Claude Opus 5.5 cost?

$4 per million input tokens and $20 per million output tokens, with cache reads at $0.20 per million, according to Anthropic's announcement.

What is the context window of Claude Opus 5.5?

1 million tokens, with up to 128,000 output tokens, according to Anthropic's model overview.

Claude Opus 5.5 news

Large language model2 stories

Claude Opus 5.5 is a large language model released by Anthropic on 22 September 2026 as the first model in the Claude 5.5 family.

Six people in business suits pose for a group photo in front of a wooden panelled wall, with Dario Amodei third from left. — Anthropic releases Claude Sonnet 5.5, 30% faster than Sonnet 5 at the same $2 input price

AI Models28 Sep 2026, 09:00 UTC

Anthropic released Claude Sonnet 5.5 on 28 September 2026 at $2 input and $10 output per 1M tokens, cheaper cache reads and 30% faster output than Sonnet 5.

Summary

Anthropic released Claude Sonnet 5.5 on 28 September 2026 as the second model of its Claude 5.5 family. It keeps Sonnet 5's price of $2 per million input tokens and $10 per million output tokens, halves cache reads to $0.10 and generates output more than 30% faster. Anthropic reports 70.6% on Terminal-Bench 4.0 against 10.3% for Sonnet 5. It has a 1 million token context window and launched on the Claude Platform, AWS, Google Cloud and Azure.

Earlier stories

Anthropic releases Claude Opus 5.5 at $4 per 1M input tokens, 20% below Claude Opus 5
AI Models22 Sep 2026

About Claude Opus 5.5

Claude Opus 5.5 is a large language model released by Anthropic on 22 September 2026 as the first model in the Claude 5.5 family. It accepts text and images, has a 1 million token context window and is aimed at long-running agentic coding and knowledge work at a lower price than Claude Opus 5.

Reviewed 28 Oct 2026 · by Anthropic

Facts at a glance

Developer: Anthropic
Released: 22 September 2026 source
API name: claude-opus-5-5 source
Context window: 1,000,000 tokens source
Max output: 128,000 tokens source
Knowledge cutoff: June 2026 (reliable knowledge and training data) source
API price: $4 per 1M input tokens, $20 per 1M output tokens, $0.20 cache reads, $5 cache writes source
Retirement: Not sooner than 22 September 2027 source

More about Claude Opus 5.5 (show)

What Claude Opus 5.5 is used for

Anthropic positions Opus 5.5 for long and sprawling jobs such as codebase-wide migrations and audits, financial analysis and research reports. Thinking is adaptive and always on, with medium as the default effort on the Claude Platform. A Fast mode with up to 2.5 times the speed costs $8 per million input tokens and $40 per million output tokens. The model is sold through the Claude Platform, Amazon Web Services, Google Cloud and Microsoft Azure, and ships with cybersecurity, biology and anti-distillation safeguards similar to those on Claude Fable 5.1.

Questions people ask

When was Claude Opus 5.5 released?: Anthropic announced it and made it available on 22 September 2026.
How much does Claude Opus 5.5 cost?: $4 per million input tokens and $20 per million output tokens, with cache reads at $0.20 per million, according to Anthropic's announcement.
What is the context window of Claude Opus 5.5?: 1 million tokens, with up to 128,000 output tokens, according to Anthropic's model overview.

Claude Opus 5.5 news

Every story about Claude Opus 5.5

Anthropic releases Claude Sonnet 5.5, 30% faster than Sonnet 5 at the same $2 input price

Earlier stories

Anthropic releases Claude Opus 5.5 at $4 per 1M input tokens, 20% below Claude Opus 5